The invention relates to a release agent for rolls and to a method for improving the release properties of rolls. In particular, the invention is directed to a release agent for rolls like press rolls in paper making and a method for improving the release properties of such rolls.
In many technical processes, continuous materials like films, webs etc. are passed over rolls. Depending on the conditions (temperature, pressure, moisture content etc.), the continuous material more or less adheres to the roll so that a certain release force is required to remove the continuous materials from the roll. Therefore, such rolls are often treated with release agents to lower said release force and to facilitate removal of the continuous material from the roll. The composition of such release agents differs widely depending on the nature of the continuous material passed over the roll, the material and the surface state of the roll and the processing conditions. Generally speaking, such agents include release active agents, often also called lubricants. Usually such agents are used pure or in form of an emulsion.
A problem often involved in the passing of a continuous material over rolls is that deposits are formed on the surface of the rolls originating from the ingredients or contaminants of the continuous material. Such deposits adversely affect the performance of the rolls and eventually result in stopping the process so that the rolls can be cleaned. To avoid such cleaning or to at least increase the intervals of such cleaning interruptions, deposit preventing agents are used, the composition of which depends on the specific process, but mostly includes a polymeric substance.
Since known release agents and deposit preventing agents are often not fully satisfactory, it is an object of the present invention to provide an improved release agent for rolls and a method using said agent for improving the release properties of rolls. It is a further object of the invention to improve the efficiency of substances used for preventing deposits on rolls.
Thus, the invention relates to a composition in form of a microemulsion which comprises one or more release active components and upon dilution with water is useful as a release agent for press rolls in papermaking systems, which is characterized in that it breaks upon dilution with water.
Further, the invention relates to a composition which comprises one or more release active components, forms a microemulsion upon addition of an appropriate amount of water, and upon further dilution with water is useful as a release agent for press rolls in papermaking systems, which is characterized in that the microemulsion breaks upon dilution with water.
Furthermore, the invention relates to a method for improving the release properties of rolls like press rolls in papermaking, which is characterized by diluting a microemulsion according to the invention with water to break the microemulsion and applying the diluted microamulsion to the roll.
Preferred embodiments and advantages of the invention will become apparent from the following detailed description of the invention and the claims.